The pack download comes with a vmf called frontline_demo (in the mapsrc folder) that you can open in Hammer to see how all the entities are set up. If you look at the logic_relays near control points 1 and 4, you'll see that they contain a list of all the events (outputs) that happen during a "shot". To put it simply, each "shot" is made up of the tank model playing an animation, a separate explosion where it "shoots," and some other effects like particles and sounds.